Riding 25mm clincher tires on rims with a 21mm inner-width?

[rice rocket]

Originally Posted by RoosterCogset

How does this work? Most wheel manufacturers aren't also tire manufacturers.

What?

[JMT3]

I’m sure my wheels on my T3 are that dimension. My 25 X 700 Continental 5000S’s measure 28mm since they stretch.

[fignon's barber]

Prior to the "what's the widest tire I can fit" movement, almost everyone on 21mm internal rims rode 25mm tires.

[RoosterCogset]

Originally Posted by rice rocket

What?

Who do you believe, the tire maker or the wheelmaker, as to what is safe and appropriate when their guidance differs?

[Mikej]

Question - is the op concerned the 25mm tire on a 21mm rim is too big or too small? What’s the widest tire for a 21mm rim?

[rice rocket]

Originally Posted by RoosterCogset

Who do you believe, the tire maker or the wheelmaker, as to what is safe and appropriate when their guidance differs?

Only reason a wheel manufacturer input would ever come into play is if they messed up the critical dimensions of the rim and deviate from the prescribed ETRTO standard.

Tire construction can differ enough that it yields an unsuitable profile if installed on too narrow or too wide of a rim. You can end up with a tippy-feeling bike, or end up riding on the sidewall.


BTW, this exact same thing happened 30 years ago in the motorcycle world. End users thought they knew better and started stretching all sorts of mismatched tires onto rims that were too squat and gave too flat a profile, and everyone ended up with terrible handling bikes that didn't turn.

[slowpoke]

Originally Posted by RoosterCogset

With tubes or tubeless? Impacts the max recommended pressure you can use.

Thanks for the Mavic chart! Tubes for sure--tubeless under 32mm is too risky for my personal tolerance as a former retrogrouch.

Originally Posted by fignon's barber

Prior to the "what's the widest tire I can fit" movement, almost everyone on 21mm internal rims rode 25mm tires.

Feel like during that time, the Belgium C2 was the rim and that had a whooping 18mm. By the time the Plus came around, thicc-curious riders were already flirting with discs.

Originally Posted by Mikej

Question - is the op concerned the 25mm tire on a 21mm rim is too big or too small? What’s the widest tire for a 21mm rim?

The 25mm tire being too narrow. Some rim/tire charts recommend 28mm tires minimum on 21mm inner width rims.